Abstract: A partially color corrected projection lens having three groups comprising from the image end a first group serving to correct aberrations, a second group supplying essentially all of the positive power of the lens and a third negative group where the second group comprises two positive elements with a negative element therebetween.

Abstract: A wide angle projection lens which comprises from the image end a first lens unit of negative power having at least one aspheric surface, a second positive lens unit comprising at least two elements and a third negative element having an aspheric concave to the image, where the first lens unit provides negative power to the overall lens and serves as an aberration corrector including some field curvature.

Abstract: A projection lens for a cathode ray tube consisting from the image end of a first lens unit including an element of overall meniscus shape and of positive power at the optical axis, a second lens unit which includes of a biconvex element and supplies the majority of the positive optical power of the lens, the biconvex element being of glass and having spheric surfaces, a third lens unit adjacent the cathode ray tube having a strongly concave image side surface and serving as a field flattener, and a corrector lens unit having at least one aspheric surface, the corrector unit being axially spaced from the second lens unit a distance such that the axial marginal rays from the second lens unit, as traced from the long cojugate intersect the image side surface of the corrector unit at a height from the optical axis that is less than the clear aperture of said corrector lens unit. The corrector lens unit is shaped to correct for off-axis aberrations above the intersection.

Abstract: A filling and weighing system and method for particulate matter in which the particulate matter in powder form is electrically charged and electrically directed to a container on a weight-frequency sensitive balance. The frequency shift of the balance is a measure of the weight of the powder in the container and when a predetermined frequency shift occurs, this is a measure of a predetermined weight of the powder in the container.

Abstract: A zoom lens having a range of equivalent focal lengths (EFL) which extend from a dimension above the diagonal of the film plane of the lens to a telephoto focal length, where the lens comprises three groups of which two are movable to vary the EFL.

Abstract: A projection lens for a cathode ray tube consisting from the image end of a first lens unit including an element of overall meniscus shape and of positive power at the optical axis, the first lens unit has an object side surface convex to the aperture stop, a second lens unit which consists of a biconvex element and supplies the majority of the positive optical power of the lens, the biconvex element beng of glass and having spheric surfaces, a third lens unit adjacent the cathode ray tube having a strongly concave image side surface and serving as a field flattener, the axial spacing between the first lens unit and said second lens unit also contributing to correction of field curvature, and a corrector lens unit having image side surface convex toward the aperture stop. The surfaces of the first lens unit and the corrector lens unit which are both convex to the aperture stop contribute to correction of sagittal oblique spherical aberration.

Abstract: A teaching system utilizing prerecorded tape which is prepared in sectors with a message segment and position indicators in the form of transparent windows which are photoelectrically detected. After a message or question is played, a first window is detected by a first detector and the tape drive motor is deenergized with another window positioned before one of a plurality of other detectors. The operator then attempts to answer or identify the message by making a selection corresponding to one of the plurality of detectors, and if a correct answer is given, a signal is given to the operator. All of the photoelectric detecting devices are on a carrier which is removably mounted to a cassette.

Abstract: A lens of variable equivalent focal length where two lens groups located on either side of an aperture defining means move relative to the aperture defining means, and a lens group of positive power is positioned close to the aperture defining means. The aperture defining means and the associated positive power group may either be stationary or move with change in equivalent focal length.